Regulation of cell differentiation by the Drosophila Jun kinase cascade.

Recent studies have defined a new Drosophila Jun amino-terminal kinase (DJNK) pathway. The first role that has been uncovered for this pathway is the control of cell differentiation and morphogenesis during the process of dorsal closure. This phosphorylation cascade has been conserved during evolution and several reports suggest that it becomes activated in response to the action of small GTPases. DJNK signalling impinges on transcription factors as DJun and Anterior open and eventually controls the expression of target genes such as decapentaplegic and puckered. Important progress has been made in the study of the coordination of DJNK and Decapentaplegic signalling during dorsal closure and their role in the control of cell shape changes--and possibly cell polarity--by promoting cytoskeletal changes.